Optical Magnus effect in metamaterials fabricated from ferromagnetic microwires

In homogeneous negative phase velocity media, the Doppler and Cherenkov-Vavilov effects and the refraction and pressure of light are anomalous: they are inverse with respect to the corresponding effects in conventional media. Using the geometrical optics approximation, it is shown that the optical Magnus effect in inhomogeneous negative phase velocity media is also anomalous. The effect is demonstrated by considering a metamaterial consisting of parallel amorphous ferromagnetic microwires in a magnetic field. The metamaterial proves to be a left-handed one in the realistic region of the electromagnetic spectrum. The optical properties of such a left-handed medium can be controlled by the external magnetic field.     

Diffractive vector meson production at HERA: From soft to hard QCD

Experimental results from HERA on diffractive vector meson production and their theoretical interpretation within microscopic QCD are reviewed with an emphasis on the BFKL color dipole and k _T -factorization approaches. The text was submitted by the authors in English.     

Generation of H− ions in a low-pressure xenon-hydrogen discharge. I

A theory of a low-pressure discharge in a xenon-molecular hydrogen mixture is developed. It is shown that, in such a discharge, at an interelectrode distance of L = 1 cm and a total plasma pressure of p ₀ ～ 1 Torr, the density of negative hydrogen ions produced via the dissociative attachment of thermal electrons to vibrationally excited molecules H₂ can reach a value as high as N_H ^? ≥ 10¹² cm^?3. According to calculations, the electron temperature in discharge operating regimes under study attains T _e ≈ 1?2 eV, which corresponds to the maximum of the e-v exchange rate constant of H₂ molecules. This ensures a relatively high rate of vibrational pumping of H₂ molecules in the discharge.     

Rational functions of best uniform approximation and holomorphic continuation of functions

Let f be a function, continuous and real valued on the segment Δ, Δ ⊂ (−∞, ∞) and {R_n} be the sequence of the rational functions of best uniform approximation to f on Δ of order (n, n). In the present work, the convergence of {R_n} in the complex plane is considered for the special caseswhen the poles (or the zeros, respectively) of {R_n} accumulate in the terms of weak convergence of measures to acompact set of zero capacity. As a consequence, sufficient conditions for the holomorphic and the meromorphic continuability of f are given. The work is supported by Project 69 with Ministry of Science and Education, Bulgaria.     

Comparison theorems for weak splittings of bounded operators

Summary Comparison theorems for weak splittings of bounded operators are presented. These theorems extend the classical comparison theorem for regular splittings of matrices by Varga, the less known result by Wonicki, and the recent results for regular and weak regular splittings of matrices by Neumann and Plemmons, Elsner, and Lanzkron, Rose and Szyld. The hypotheses of the theorems presented here are weaker and the theorems hold for general Banach spaces and rather general cones. Hypotheses are given which provide strict inequalities for the comparisons. It is also shown that the comparison theorem by Alefeld and Volkmann applies exclusively to monotone sequences of iterates and is not equivalent to the comparison of the spectral radius of the iteration operators.This work was supported by the National Science Foundation grants DMS-8807338 and INT-8918502     

On the solution of singular linear systems of algebraic equations by semiiterative methods

Summary For a square matrixT ^n,n , where (I–T) is possibly singular, we investigate the solution of the linear fixed point problemx=T x+c by applying semiiterative methods (SIM's) to the basic iterationx ₀ ⁿ ,x _k T c _k–1+c(k1). Such problems arise if one splits the coefficient matrix of a linear systemA x=b of algebraic equations according toA=M–N (M nonsingular) which leads tox=M ^–1 N x+M ^–1 bT x+c. Even ifx=T x+c is consistent there are cases where the basic iteration fails to converge, namely ifT possesses eigenvalues 1 with ||1, or if =1 is an eigenvalue ofT with nonlinear elementary divisors. In these cases — and also ifx=T x+c is incompatible — we derive necessary and sufficient conditions implying that a SIM tends to a vector which can be described in terms of the Drazin inverse of (I–T). We further give conditions under which is a solution or a least squares solution of (I–T)x=c.Research supported in part by the Alexander von Humboldt-Stiftung     

Geschwindigkeit der Verdünnung flüssiger Filme

Colloid and Polymer Science - Die Verdünnung eines mit löslichen Tensiden stabilisierten freien flüssigen Filmes wurde mit hydrodynamischen Methoden unter Berücksichtigung der...     

Topochemical investigations of peptide systems

The basic principles of the topochemical approach to the investigation of the structure-function relation in peptide systems are formulated. This approach makes use of the new possibility of transforming natural peptides, consisting in the modification of the molecule as a whole and utilization of the resultant analogs to elucidate the boundaries of the stereoelectronic complementarity of the biologically active peptide to the corresponding receptor. In particular, on the example of depsipeptide antibiotics and their topochemical analogs the fruitfulness of using such compounds as tools in elucidating the physicochemical basis of functioning of biological membranes is shown. The topochemical principle has also been applied in preparing specific competitive inhibitors of proteolytic enzymes, whose study may shed light on the nature of the forces binding the substrate to the contact site of the corresponding enzyme.